The purpose of the present project was to probe for the relationship between alpha-receptors in discrete areas of rat brain and blood pressure regulation. Specially bred WKY, SHR and SHR/SP rats were used for this investigation. The specific areas removed and analyzed were the hypothalamus, hippocampus, and area containing the locus coerulus and the A2 area containing the nucleus tractus solitarius. The ligands used for the analysis were the antagonist, WB4101 and the agonist clonidine. There were no differences in WB 4101 binding in any of the areas examined. Clonidine binding studies, however, did reverse some differences; significantly decreased binding in the hippocampus, L. C. and A2 region of the SHR rats compared to control WKY. Only the hippocampus of the SHR/SP showed significantly less binding than control. Present investigations are pursuing the kinetic characteristics of this reduced binding.